Experimental study of irrigation rate, ODC and intrarenal temperature in superpulse fiber thulium laser lithotripsy

Experimental study of irrigation rate, ODC and intrarenal temperature in superpulse fiber thulium laser lithotripsy | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Experimental study of irrigation rate, ODC and intrarenal temperature in superpulse fiber thulium laser lithotripsy tianfu ding, jianxng li This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4724781/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 23 Oct, 2024 Read the published version in World Journal of Urology → Version 1 posted 9 You are reading this latest preprint version Abstract The present study aimed to examine the relationship of irrigation velocity, operator duty cycle (ODC), and intrarenal temperature during extracorporeal shockwave lithotripsy with a superpulse fiber thulium laser. Calcium oxalate monohydrate stones were implanted in the renal pelvis of fresh pig kidneys. Puncture technology was used to place a temperature probe accurately in the renal parenchyma about 2 mm away from the stone. To simulate the temperature at which a human body is exposed, that is, 37°C, the experiment was executed in an equilibrated laboratory at a constant temperature of 25°C with 60% humidity. The power of the laser varied between 10W and 30W; that of the irrigation varied from 10 to 30 ml/min. The time that the laser was applied was set at 120 s. Changes in the temperature were recorded online. A direct proportionality of temperature in the kidney to the rate of irrigation has been reported between 10 W and 30 W laser powers. The percentage ratio of the rate of irrigation and power in the laser is 1:1, which can keep the temperature in the kidney at a safe level. More specifically, at a laser power of 20 W and irrigation of 10 ml/min, the temperature inside the kidney increases sharply with the increase in ODC. By decreasing the ratio of ODC, the increase of temperature inside the kidney can be brought to a great reduction. The ratio of laser power to that of irrigation speed should be 1:1; hence, damage or injury to kidney tissue can be efficiently prevented from thermal changes. superpulse fiber thulium laser operator duty cycle (ODC) irrigation rate Intrarenal temperature Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Introduction The continuous development of medical technology has resulted in the continued improvement of laser lithotripsy, which is now a mature treatment technique. Superpulsed fiber thulium laser with a 1940-nm wavelength has come to be one of the important candidates for lithotripsy. Due to the proximity of this wavelength to the absorption peak of water, the absorption coefficient of that wavelength in aqueous solutions is markedly higher than the conventional holmium laser at 2100 nm. This gives this wavelength a substantial edge over others in lithotripsy efficiency[1, 2]. Today, medical guidelines recommend the use of holmium lasers not only for home but also for treatment abroad because of the wide range of applications and good outcomes in the procedure of lithotripsy[3]. What is more important is that besides showing stone-crushing efficiency superior to that with the holmium laser, the super-pulsed fiber thulium laser also represents a new breakthrough in the treatment of the urinary tract stone, which features lower stone recoil force and thinner fiber diameter[4]. These features would thus indicate that the super-pulsed fiber thulium laser could be well applied and developed in the field of urinary stone treatment. The development of lithotripsy technology always attaches importance to the safety issue of laser lithotripsy as much as the stone comminution effect does. This work is aimed to optimize the temperature control and the irrigation flow rate during the process of laser lithotripsy to accomplish safe and effective therapy. The experimental study results showed that changes in irrigation rates greatly influenced the temperature in the kidney at laser powers between 10 W to 30 W. In clear terms, at a laser power of 20 W and the irrigation level of 10 ml/min, there is a significant increase in temperature within the kidney as the ODC starts to rise. In fact, a decrease in the ODC ratio can bring about a remarkable reduction in intrarenal temperature elevation. The application of 1:1 lithotripsy power and irrigation rate will prevent thermal injury to the renal tissue tremendously. Materials and methods In vitro modeling Preparation of the required apparatus and materials was done prior to the experiment. These were fresh isolated porcine kidneys, a disposable electronic ureteroscope (F7.4 at the proximal end, F8.6 at the distal end), an F11/13 ureteroscope sheath, a superpulse thulium laser device with a 200 µm diameter laser fiber, a multi-channel real-time thermometer, a precision laboratory water pump, a thermostatic water bath, saline solution, and a variety of other surgical instruments. The kidney was mounted onto the experimental frame and a temperature probe placed into the renal parenchyma, about 2 mm away from the stone, using the puncture technique. A clinical specimen of calcium oxalate monohydrate stone (CT value: 890 ± 123 HU) was placed in the renal pelvis, and the ureteroscope sheath was inserted. The disposable electronic ureteroscope was then passed through the sheath of the ureteroscope to enable real-time visualization and manipulation. All of these were further submersed into a thermostatic water bath very close to the temperature of the human body at 37°C. The continuity of water inside and around the kidney was maintained by a precision laboratory water pump along with normal saline. On the other hand, the super-pulse thulium laser device was turned on and lithotripsy procedure performed using a 200 micrometer laser fiber. The process was visualized and captured real-time, and the heat changes in the kidney were monitored. Experimental procedures The laboratory has a stable temperature maintained at 25°C, and relative humidity is 60%. The laser lithotripsy power was set to 10W (1.0J×10Hz, 0.1J×100Hz), 15W (1.5J×10Hz, 0.15J×100Hz), 20W (2.0J×10Hz, 0.1J×200Hz), 25W (2.5J×10Hz, 0.1J×250Hz), and 30W (1.0J×10Hz, 0. The experiment was done using a 1J×300Hz apparatus, with a irrigation rate of 10. A disposable electronic F8.6 ureteroscope and an F11/13 ureteral sheath were used. Strategies were set up for five ODC modes: ODC50% (excitation with the laser for 10 seconds and off for 10 seconds), ODC60% (excitation with the laser for 12 seconds and off for 8 seconds), ODC70% (excitation with the laser for 14 seconds and off for 6 seconds), and ODC80% (excitation with the laser for 16 seconds and off for 4 seconds) protocols were used. The ODC90% strategy was therefore such that the laser was on for 18 seconds and off for 2 seconds. So in the ODC100% strategy, the laser was permanently on such that there was no off period. Each of this was repeated for 20 seconds, which made up one operational cycle. This cycle was repeated six times to create a group of experiments. The total number of each parameter group was repeated five times for each group to assure data correctness and repeatability. Data collection and analysis The experiments have been conducted at least in quintuplicate, and the data are given as averages. Data were graphed using ggplot2 in R version 4.3.3. Values are presented as mean ± standard deviation. Statistical analysis was conducted by paired t-test between two groups and nonparametric rank sum tests using multiple samples for multiple groups. The significant difference was set at p < 0.05. Results Changes in intrarenal temperature during continuous laser lithotripsy From that case, it was observed that within the kidney, under a continuous laser excitation time of 120 s, there was a major significant interaction effect between the different lithotripsy powers and irrigation rates for the temperature. The temperature specifically in this case of stone-crushing power of 10 W in the kidney stabilized at 35°C, 32.7°C, 30.6°C, 29.0°C, and 28.1°C. The corresponding irrigation rates were 10 ml/min, 15 ml/min, 20 ml/min, 25 ml/min, and 30 ml/min. Of course, none of these was above the safe limit, as can be seen in Fig. 2 . For a irrigation of 10 ml/min, temperature still rose in the kidney at a stone-crushing power of 15 W. The temperature stabilized at 37.5°C, 34.2°C, 31.8°C, and 30.3°C at irrigation rates of 15 ml/min, 20 ml/min, 25 ml/min, and 30 ml/min respectively (Fig. 3 ). Again, irrigation over this temperature range resulted in steady states at 37.5°C and 34.2°C for irrigation rates of. At 20 W of stone-crushing power, the temperature rose greatly inside the kidney, but it plateaued at irrigation rates of 10 ml/min and 15 ml/min, with the mean irrigation values shown to be 37.6°C, 34.8°C, and 32.9°C at 20 ml/min, 25 ml/min, and 30 ml/min of irrigation rates, respectively (Fig. 4 ). During the stone-crushing power of 25 W, the temperature of the kidney continued to increase with irrigation rates of 10 ml/min, 15 ml/min, and 20 ml/min, but for the irrigation rates of 25 ml/min and 30 ml/min, the temperature of the kidney was maintained at 37.6°C and 35.8°C, respectively (Fig. 5 ). At a stone-crushing power of 30 W, temperature continued to rise within the kidney at irrigation rates of 10 ml/min, 15 ml/min, 20 ml/min, and 25 ml/min while remaining constant at 37.8°C at 30 ml/min (Fig. 6 ). Interesting to note that, none of these temperatures crossed the safety threshold. Changes in intrarenal temperature under different ODC ratios Based on the 20 W power and a irrigation velocity of 10 ml/min, in a cycle of 2 minutes, six different steady states were found for a change in kidney temperature. The results showed that an increase in the ODC ratio was accompanied by increasing kidney temperature during all of the steady-state periods. Initial steady-state temperatures were 33.4 ± 1.58°C for the ODC 50% condition and 34.0 ± 1.91°C for ODC 60%. By temperature, it read 34 ± 1.91°C; at 70% ODC ratio, the temperature is recorded as: The average was 34.8 ± 1.24°C; at 80% ODC ratio, the average came out to be: The temperature was recorded at 35.7 ± 1.03°C; at ODC of 90%. The average was 36.4 ± 0.49°C (Table 1). The kidney temperature resulted in some definite value of steady state and was constant, showing no temperature increase during the process of time under 70% and less ODC maintenance. However, with more than 80% of the ODC, a kidney temperature increase to the second point of steady state can be seen in Fig. 7 . The safe threshold of time for reaching the renal temperature was 76.4 ± 1.14 s at an ODC ratio of 80%, 43.6 ± 1.52 s at 90%, and 38.0 ± 1.58 s at 100% (F = 1058.10, p < 0.01; Table 2). Discussion The tremendous progress in medical science and technology has seen revolutionary changes in high-power laser technology. The super-pulsed fiber thulium laser technology, with a wavelength of 1940 nm, is closer to the absorption peak of water than the conventional holmium laser at 2100 nm[1, 5]. This positioning confers many technological advantages to the thulium laser: low energy threshold and efficiency in crushing stones. It has a high pulse frequency with low pulse energy, leading to small fragments during lithotripsy. This is of advantage for the complete powderization of the stones[4]. Besides, super-pulse thulium fiber laser characterizes a smaller fiber core diameter, adjustable pulse shape, and adjustable pulse width duration. These features do not just reduce the recoil force which is exerted by the stones while lithotripsy but also significantly increase the accuracy and safety of the procedure[1, 2]. The use of flexible ureteroscopes introduces the operability and flexibility of the procedure. Studies conducted earlier have shown that there is a considerable amount of cell necrosis in the human tissue above 43°C temvperature and cell death further increases to 45°C[6]. At a temperature of 60°C, the proteins present in the tissue are irreversibly denatured; therefore, the structure of the tissue is permanently destroyed and its function is lost. This is why, to some extent, this is also considered as the temperature threshold for human tissue at 43°C. During extracorporeal shock wave lithotripsy, the irrigation rate plays a very important factor in determining the temperature of the tissue[7]. The use of high irrigation rates will help avoid increased temperatures inside the kidney. A irrigation rate of 100 ml/min will maintain the temperature so that, even if the laser works continuously for one minute, the temperature does not exceed 38.5°C[8]. But if the irrigation rate is too high, the intra-renal pressure will be increased, leading to postoperative pain and the patient being more prone to infection[9–11]. On the contrary, an inadequate irrigation rate might end up causing a high intraoperative temperature, leading to thermal injury in the tissues and affecting the visual field with an inability to wash away the stone powder in time, thus causing further damage to the tissues. And therefore, it is very important to measure the irrigation rate reasonably so that a surgical intervention in the patient can be safely made. In this experiment, we made a detailed observation and analysis of the temperature control used in laser lithotripsy. 10W lithotripsy power and 10ml/min irrigation rate kept the temperature of the kidney steady at a plateau in the early stage of the experiment, wherein this constant temperature was always below the safety threshold. The power of the laser had been increased to 15W while proceeding with the experiment, although the irrigation rate remained the same. The temperature plateau reached 44°C in the kidney, which was beyond the limit for safe human tissue. This damage was then effectively contained by increasing irrigation to a flow of 15 ml/min, such that the temperature was maintained at safe levels to prevent thermal injury. The results of the experiment show that with an increase in power, the temperature in the kidney grows appropriately to this change; conversely, an increase in the irrigation rate results in a decrease of the temperature in the kidney. Our observations correspond to the findings of Winship et al. [12], who conducted their experiments using 3.6 W, 6.4 W, 10 W, 16 W, and 20 W laser power with irrigation pressures of 0, 100, and 200 mmHg. These authors concluded that both the temperature in the kidney and the speed of irrigation determine the conducted temperature: the higher the laser power, the higher the temperature in the kidney; the faster the irrigation rate, the lower the temperature in the kidney [11]. The most striking result from this experiment is that when lithotripsy power and irrigation speed are varied together at a 1:1 ratio, the plateau temperature in the kidney stays below the safety threshold for all conditions. This approach is not only superior to the safety of the procedure but also provides physicians with a new way to adjust operational parameters in maximizing the benefit of lithotripsy while minimizing the possibility of thermal injury to the patient's kidney. In our work, the 20 W lithotripter power and an irrigation flow rate of 10 mL/min were considered, paying particular attention to ODC values in a large range from 50–100%. This phenomenon is just the same as the classical sawtooth fluctuation wave which is corresponding to the laser periodical activation: the temperature in liquid increases rapidly when the laser is activated and decreases slowly to form a plateau when it is deactivated. The ODC ratio of the kidney showed a significantly raised level at the steady-state. This is similar to what was also observed in Louters et al. [13], so that a higher ODC increases temperature and energy release markedly. The steady-state renal temperature shows a trend of leveling off after attaining some value and does not increase further in case the ODC was kept below 70%. On the other hand, steady-state renal temperature increased to an increasing value after an ODC higher than 80%, and this may reflect increasing heat accumulation effect. It was also observed that a marked reduction in ODC, above an ODC of about 80%, considerably prolonged the time for which renal temperature to reach the safety threshold. This is likely due to the concordance with the results of Wanderling et al. [14]. The current theory is supported by the experimental results, which demonstrate that, over the very fine-tuning of the ODC required to minimize continuous activation time of the laser, the laser may be used for a greater length of time without crossing the safety temperature limit. One interesting point must be considered in this trial. The experiment used a fixed superpulsed thulium fiber laser, one diameter of the fiber, and a ureteral guide sheath with a flexible ureteroscope. The effect of fiber diameter on temperature and size of the soft sheath is an area for future research. In addition, the fact that this was an in vitro experiment does not bring into play the physiological factors in the changes in temperature, like renal irrigation and urine production. More studies are essential to clarify whether experiments on animals present a solution to this problem. In a nut shell, the outcome of the study has indicated that the decrease in ODC ratio from applying extracorporeal shock wave lithotripsy can have the effect of substantially reducing the rise in renal temperature. By adjusting the power in direct proportion to the lithotripsy and the irrigation rate in a 1:1 ratio, the renal temperature can be effectively kept within a safe range so as not to generate thermal damage to the tissue of the kidney. This may provide a new safe and effective method for clinical application in surgery. Conclusion Therefore, reducing the ratio of ODC allows substantial relief in renal temperature elevation during super-pulse optical fiber thulium laser lithotripsy. When gravel power and irrigation speed have a 1:1 adjustment ratio, it can effectively keep renal temperature within safe limits, guarding against thermal injury of kidney tissue. Declarations Funding There was no source of funding for this project. Author Contribution Ding tianfu.Xu zheng.and Li jianxing. wrote the main manuscript text. Huang zhongyue. Xiao bo. and Huweiguo prepared all figures and table. All authors reviewed the manuscript References Ventimiglia E, Robesti D, Bevilacqua L, Tondelli E, Oliva I, Orecchia L, et al. What to expect from the novel pulsed thulium:YAG laser? A systematic review of endourological applications. World J Urol. 2023. doi: 10.1007/s00345-023-04580-z. Kronenberg P, Traxer O. The laser of the future: reality and expectations about the new thulium fiber laser-a systematic review. Translational andrology and urology. 2019;8(Suppl 4):S398-s417. doi: 10.21037/tau.2019.08.01. Türk C, Petřík A, Sarica K, Seitz C, Skolarikos A, Straub M, et al. EAU Guidelines on Interventional Treatment for Urolithiasis. European urology. 2016;69(3):475 − 82. doi: 10.1016/j.eururo.2015.07.041. Traxer OA-O, Keller EA-O. Thulium fiber laser: the new player for kidney stone treatment? A comparison with Holmium:YAG laser. (1433–8726 (Electronic)). Peng Y, Liu M, Ming S, Yu W, Li L, Lu C, et al. Safety of a Novel Thulium Fiber Laser for Lithotripsy: An In Vitro Study on the Thermal Effect and Its Impact Factor. J Endourol. 2020;34(1):88–92. doi: 10.1089/end.2019.0426. Sapareto SA, Dewey WC. Thermal dose determination in cancer therapy. Int J Radiat Oncol Biol Phys. 1984;10(6):787–800. doi: 10.1016/0360-3016(84)90379-1. Panthier F, Pauchard F, Traxer O. Retrograde intra renal surgery and safety: pressure and temperature. A systematic review. Current opinion in urology. 2023;33(4):308 − 17. doi: 10.1097/mou.0000000000001102. Aldoukhi AH, Ghani KR, Hall TL, Roberts WW. Thermal Response to High-Power Holmium Laser Lithotripsy. J Endourol. 2017;31(12):1308-12. doi: 10.1089/end.2017.0679. Rashid AO, Fakhulddin SS. Risk factors for fever and sepsis after percutaneous nephrolithotomy. Asian J Urol. 2016;3(2):82 − 7. doi: 10.1016/j.ajur.2016.03.001. Alsyouf M Fau - Abourbih S, Abourbih S Fau - West B, West B Fau - Hodgson H, Hodgson H Fau - Baldwin DD, Baldwin DD. Elevated Renal Pelvic Pressures during Percutaneous Nephrolithotomy Risk Higher Postoperative Pain and Longer Hospital Stay. (1527–3792 (Electronic)). Tokas T, Herrmann TRW, Skolarikos A, Nagele U. Pressure matters: intrarenal pressures during normal and pathological conditions, and impact of increased values to renal physiology. World J Urol. 2019;37(1):125 − 31. doi: 10.1007/s00345-018-2378-4. Winship B, Wollin D, Carlos E, Peters C, Li J, Terry R, et al. The Rise and Fall of High Temperatures During Ureteroscopic Holmium Laser Lithotripsy. J Endourol. 2019;33(10):794-9. doi: 10.1089/end.2019.0084. Louters MM, Dau JJ, Hall TL, Ghani KR, Roberts WW. Laser operator duty cycle effect on temperature and thermal dose: in-vitro study. World J Urol. 2022;40(6):1575-80. doi: 10.1007/s00345-022-03967-8. Wanderling C, Saxton A, Phan D, Doersch K, Shepard L, Schuler N, et al. WATTS happening? Evaluation of thermal dose during holmium laser lithotripsy in a high-fidelity anatomic model. World J Urol. 2024;42(1):157. doi: 10.1007/s00345-024-04821-9. Tables ODC S−S First time Second time Third time Fourth time Fifth time Sixth time 50% 33.4 ± 1.58 36.2 ± 0.34 39.2 ± 0.42 40 ± 0.83 40 ± 0.63 40 ± 0.84 60% 34.0 ± 1.91 37 ± 1.29 39.5 ± 1.34 41 ± 1.01 41 ± 0.68 41 ± 0.57 70% 34.8 ± 1.24 37.7 ± 0.59 40.5 ± 0.39 42 ± 0.82 42 ± 0.47 42 ± 1.01 80% 35.7 ± 1.03 40 ± 1.25 42.7 ± 1.14 44.1 ± 0.53 45.8 ± 0.53 46.5 ± 1.47 90% 36.4 ± 0.49 39.6 ± 1.16 42 ± 1.32 43.9 ± 1.18 46.2 ± 1.43 47.4 ± 1.58 Table.1 The laser gravel power is set to 20W and the irrigation speed is 10ml/min, the steady-state temperature in the kidney under the working cycle (ODC) of different agents (℃) Time ODC 80% 90% 100% F p Time to reach the safety threshold 76.4 ± 1.14 43.6 ± 1.52 38.0 ± 1.58 1058.10 <0.01 Table.2 The time required for different proportions of ODC to reach the safety threshold(s) Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 23 Oct, 2024 Read the published version in World Journal of Urology → Version 1 posted Editorial decision: Revision requested 15 Aug, 2024 Reviews received at journal 31 Jul, 2024 Reviewers agreed at journal 22 Jul, 2024 Reviews received at journal 22 Jul, 2024 Reviewers agreed at journal 21 Jul, 2024 Reviewers invited by journal 19 Jul, 2024 Editor assigned by journal 16 Jul, 2024 Submission checks completed at journal 16 Jul, 2024 First submitted to journal 11 Jul, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4724781","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":334687785,"identity":"36f6323d-88ae-4af6-b35f-de6317a37133","order_by":0,"name":"tianfu ding","email":"","orcid":"","institution":"Beijing Tsinghua Chang Gung Hospital","correspondingAuthor":false,"prefix":"","firstName":"tianfu","middleName":"","lastName":"ding","suffix":""},{"id":334687786,"identity":"d9ae2aa3-8629-4e61-b529-0b1a1849270f","order_by":1,"name":"jianxng 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4","display":"","copyAsset":false,"role":"figure","size":65266,"visible":true,"origin":"","legend":"\u003cp\u003eRenal temperature at each irrigation speed at 20W of gravel power\u003c/p\u003e","description":"","filename":"Picture4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4724781/v1/2aeceda341a73a4c8986d549.jpg"},{"id":62152628,"identity":"33588634-a0dc-41bf-8354-cd1eaee7e7b0","added_by":"auto","created_at":"2024-08-09 20:51:28","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":73772,"visible":true,"origin":"","legend":"\u003cp\u003eRenal temperature at each irrigation speed at 25W of gravel power\u003c/p\u003e","description":"","filename":"Picture5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4724781/v1/a21fef1f2964f5c28669149d.jpg"},{"id":62152627,"identity":"ec889cd5-b671-4fa4-a4f2-a5c7d8aac3c1","added_by":"auto","created_at":"2024-08-09 20:51:28","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":77927,"visible":true,"origin":"","legend":"\u003cp\u003eRenal temperature at each irrigation speed at 30W of gravel power\u003c/p\u003e","description":"","filename":"Picture6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4724781/v1/8b03f80ac346c4d85dfdf6d2.jpg"},{"id":62152625,"identity":"81cd652d-cf00-4bbe-8cc8-9e63ebfb2f67","added_by":"auto","created_at":"2024-08-09 20:51:27","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":115813,"visible":true,"origin":"","legend":"\u003cp\u003eCurve of renal temperature during the working cycle (ODC) of different proportions (laser power set to 20W, irrigation speed is 10ml/min)\u003c/p\u003e","description":"","filename":"Picture7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4724781/v1/0a69afc8800675dbd33587d4.jpg"},{"id":67682141,"identity":"7cd41294-d958-4a15-a63b-43e20df33ea1","added_by":"auto","created_at":"2024-10-28 16:13:27","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":987930,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4724781/v1/37f5f7e8-9eb2-4cfa-8cd1-bff490834b93.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Experimental study of irrigation rate, ODC and intrarenal temperature in superpulse fiber thulium laser lithotripsy","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe continuous development of medical technology has resulted in the continued improvement of laser lithotripsy, which is now a mature treatment technique. Superpulsed fiber thulium laser with a 1940-nm wavelength has come to be one of the important candidates for lithotripsy. Due to the proximity of this wavelength to the absorption peak of water, the absorption coefficient of that wavelength in aqueous solutions is markedly higher than the conventional holmium laser at 2100 nm. This gives this wavelength a substantial edge over others in lithotripsy efficiency[1, 2]. Today, medical guidelines recommend the use of holmium lasers not only for home but also for treatment abroad because of the wide range of applications and good outcomes in the procedure of lithotripsy[3]. What is more important is that besides showing stone-crushing efficiency superior to that with the holmium laser, the super-pulsed fiber thulium laser also represents a new breakthrough in the treatment of the urinary tract stone, which features lower stone recoil force and thinner fiber diameter[4]. These features would thus indicate that the super-pulsed fiber thulium laser could be well applied and developed in the field of urinary stone treatment. The development of lithotripsy technology always attaches importance to the safety issue of laser lithotripsy as much as the stone comminution effect does. This work is aimed to optimize the temperature control and the irrigation flow rate during the process of laser lithotripsy to accomplish safe and effective therapy. The experimental study results showed that changes in irrigation rates greatly influenced the temperature in the kidney at laser powers between 10 W to 30 W. In clear terms, at a laser power of 20 W and the irrigation level of 10 ml/min, there is a significant increase in temperature within the kidney as the ODC starts to rise. In fact, a decrease in the ODC ratio can bring about a remarkable reduction in intrarenal temperature elevation. The application of 1:1 lithotripsy power and irrigation rate will prevent thermal injury to the renal tissue tremendously.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eIn vitro modeling\u003c/h2\u003e \u003cp\u003ePreparation of the required apparatus and materials was done prior to the experiment. These were fresh isolated porcine kidneys, a disposable electronic ureteroscope (F7.4 at the proximal end, F8.6 at the distal end), an F11/13 ureteroscope sheath, a superpulse thulium laser device with a 200 \u0026micro;m diameter laser fiber, a multi-channel real-time thermometer, a precision laboratory water pump, a thermostatic water bath, saline solution, and a variety of other surgical instruments. The kidney was mounted onto the experimental frame and a temperature probe placed into the renal parenchyma, about 2 mm away from the stone, using the puncture technique. A clinical specimen of calcium oxalate monohydrate stone (CT value: 890\u0026thinsp;\u0026plusmn;\u0026thinsp;123 HU) was placed in the renal pelvis, and the ureteroscope sheath was inserted. The disposable electronic ureteroscope was then passed through the sheath of the ureteroscope to enable real-time visualization and manipulation. All of these were further submersed into a thermostatic water bath very close to the temperature of the human body at 37\u0026deg;C. The continuity of water inside and around the kidney was maintained by a precision laboratory water pump along with normal saline. On the other hand, the super-pulse thulium laser device was turned on and lithotripsy procedure performed using a 200 micrometer laser fiber. The process was visualized and captured real-time, and the heat changes in the kidney were monitored.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eExperimental procedures\u003c/h2\u003e \u003cp\u003eThe laboratory has a stable temperature maintained at 25\u0026deg;C, and relative humidity is 60%. The laser lithotripsy power was set to 10W (1.0J\u0026times;10Hz, 0.1J\u0026times;100Hz), 15W (1.5J\u0026times;10Hz, 0.15J\u0026times;100Hz), 20W (2.0J\u0026times;10Hz, 0.1J\u0026times;200Hz), 25W (2.5J\u0026times;10Hz, 0.1J\u0026times;250Hz), and 30W (1.0J\u0026times;10Hz, 0. The experiment was done using a 1J\u0026times;300Hz apparatus, with a irrigation rate of 10. A disposable electronic F8.6 ureteroscope and an F11/13 ureteral sheath were used. Strategies were set up for five ODC modes: ODC50% (excitation with the laser for 10 seconds and off for 10 seconds), ODC60% (excitation with the laser for 12 seconds and off for 8 seconds), ODC70% (excitation with the laser for 14 seconds and off for 6 seconds), and ODC80% (excitation with the laser for 16 seconds and off for 4 seconds) protocols were used. The ODC90% strategy was therefore such that the laser was on for 18 seconds and off for 2 seconds. So in the ODC100% strategy, the laser was permanently on such that there was no off period. Each of this was repeated for 20 seconds, which made up one operational cycle. This cycle was repeated six times to create a group of experiments. The total number of each parameter group was repeated five times for each group to assure data correctness and repeatability.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eData collection and analysis\u003c/h2\u003e \u003cp\u003eThe experiments have been conducted at least in quintuplicate, and the data are given as averages. Data were graphed using ggplot2 in R version 4.3.3. Values are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation. Statistical analysis was conducted by paired t-test between two groups and nonparametric rank sum tests using multiple samples for multiple groups. The significant difference was set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eChanges in intrarenal temperature during continuous laser lithotripsy\u003c/h2\u003e \u003cp\u003eFrom that case, it was observed that within the kidney, under a continuous laser excitation time of 120 s, there was a major significant interaction effect between the different lithotripsy powers and irrigation rates for the temperature. The temperature specifically in this case of stone-crushing power of 10 W in the kidney stabilized at 35\u0026deg;C, 32.7\u0026deg;C, 30.6\u0026deg;C, 29.0\u0026deg;C, and 28.1\u0026deg;C. The corresponding irrigation rates were 10 ml/min, 15 ml/min, 20 ml/min, 25 ml/min, and 30 ml/min. Of course, none of these was above the safe limit, as can be seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. For a irrigation of 10 ml/min, temperature still rose in the kidney at a stone-crushing power of 15 W. The temperature stabilized at 37.5\u0026deg;C, 34.2\u0026deg;C, 31.8\u0026deg;C, and 30.3\u0026deg;C at irrigation rates of 15 ml/min, 20 ml/min, 25 ml/min, and 30 ml/min respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Again, irrigation over this temperature range resulted in steady states at 37.5\u0026deg;C and 34.2\u0026deg;C for irrigation rates of. At 20 W of stone-crushing power, the temperature rose greatly inside the kidney, but it plateaued at irrigation rates of 10 ml/min and 15 ml/min, with the mean irrigation values shown to be 37.6\u0026deg;C, 34.8\u0026deg;C, and 32.9\u0026deg;C at 20 ml/min, 25 ml/min, and 30 ml/min of irrigation rates, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). During the stone-crushing power of 25 W, the temperature of the kidney continued to increase with irrigation rates of 10 ml/min, 15 ml/min, and 20 ml/min, but for the irrigation rates of 25 ml/min and 30 ml/min, the temperature of the kidney was maintained at 37.6\u0026deg;C and 35.8\u0026deg;C, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). At a stone-crushing power of 30 W, temperature continued to rise within the kidney at irrigation rates of 10 ml/min, 15 ml/min, 20 ml/min, and 25 ml/min while remaining constant at 37.8\u0026deg;C at 30 ml/min (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). Interesting to note that, none of these temperatures crossed the safety threshold.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eChanges in intrarenal temperature under different ODC ratios\u003c/h2\u003e \u003cp\u003eBased on the 20 W power and a irrigation velocity of 10 ml/min, in a cycle of 2 minutes, six different steady states were found for a change in kidney temperature. The results showed that an increase in the ODC ratio was accompanied by increasing kidney temperature during all of the steady-state periods. Initial steady-state temperatures were 33.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.58\u0026deg;C for the ODC 50% condition and 34.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1.91\u0026deg;C for ODC 60%. By temperature, it read 34\u0026thinsp;\u0026plusmn;\u0026thinsp;1.91\u0026deg;C; at 70% ODC ratio, the temperature is recorded as: The average was 34.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.24\u0026deg;C; at 80% ODC ratio, the average came out to be: The temperature was recorded at 35.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1.03\u0026deg;C; at ODC of 90%. The average was 36.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.49\u0026deg;C (Table\u0026nbsp;1). The kidney temperature resulted in some definite value of steady state and was constant, showing no temperature increase during the process of time under 70% and less ODC maintenance. However, with more than 80% of the ODC, a kidney temperature increase to the second point of steady state can be seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e. The safe threshold of time for reaching the renal temperature was 76.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.14 s at an ODC ratio of 80%, 43.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.52 s at 90%, and 38.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1.58 s at 100% (F\u0026thinsp;=\u0026thinsp;1058.10, p\u0026thinsp;\u0026lt;\u0026thinsp;0.01; Table\u0026nbsp;2).\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe tremendous progress in medical science and technology has seen revolutionary changes in high-power laser technology. The super-pulsed fiber thulium laser technology, with a wavelength of 1940 nm, is closer to the absorption peak of water than the conventional holmium laser at 2100 nm[1, 5]. This positioning confers many technological advantages to the thulium laser: low energy threshold and efficiency in crushing stones. It has a high pulse frequency with low pulse energy, leading to small fragments during lithotripsy. This is of advantage for the complete powderization of the stones[4]. Besides, super-pulse thulium fiber laser characterizes a smaller fiber core diameter, adjustable pulse shape, and adjustable pulse width duration. These features do not just reduce the recoil force which is exerted by the stones while lithotripsy but also significantly increase the accuracy and safety of the procedure[1, 2]. The use of flexible ureteroscopes introduces the operability and flexibility of the procedure.\u003c/p\u003e \u003cp\u003eStudies conducted earlier have shown that there is a considerable amount of cell necrosis in the human tissue above 43\u0026deg;C temvperature and cell death further increases to 45\u0026deg;C[6]. At a temperature of 60\u0026deg;C, the proteins present in the tissue are irreversibly denatured; therefore, the structure of the tissue is permanently destroyed and its function is lost. This is why, to some extent, this is also considered as the temperature threshold for human tissue at 43\u0026deg;C. During extracorporeal shock wave lithotripsy, the irrigation rate plays a very important factor in determining the temperature of the tissue[7]. The use of high irrigation rates will help avoid increased temperatures inside the kidney. A irrigation rate of 100 ml/min will maintain the temperature so that, even if the laser works continuously for one minute, the temperature does not exceed 38.5\u0026deg;C[8]. But if the irrigation rate is too high, the intra-renal pressure will be increased, leading to postoperative pain and the patient being more prone to infection[9\u0026ndash;11]. On the contrary, an inadequate irrigation rate might end up causing a high intraoperative temperature, leading to thermal injury in the tissues and affecting the visual field with an inability to wash away the stone powder in time, thus causing further damage to the tissues. And therefore, it is very important to measure the irrigation rate reasonably so that a surgical intervention in the patient can be safely made. In this experiment, we made a detailed observation and analysis of the temperature control used in laser lithotripsy. 10W lithotripsy power and 10ml/min irrigation rate kept the temperature of the kidney steady at a plateau in the early stage of the experiment, wherein this constant temperature was always below the safety threshold. The power of the laser had been increased to 15W while proceeding with the experiment, although the irrigation rate remained the same. The temperature plateau reached 44\u0026deg;C in the kidney, which was beyond the limit for safe human tissue. This damage was then effectively contained by increasing irrigation to a flow of 15 ml/min, such that the temperature was maintained at safe levels to prevent thermal injury. The results of the experiment show that with an increase in power, the temperature in the kidney grows appropriately to this change; conversely, an increase in the irrigation rate results in a decrease of the temperature in the kidney. Our observations correspond to the findings of Winship et al. [12], who conducted their experiments using 3.6 W, 6.4 W, 10 W, 16 W, and 20 W laser power with irrigation pressures of 0, 100, and 200 mmHg. These authors concluded that both the temperature in the kidney and the speed of irrigation determine the conducted temperature: the higher the laser power, the higher the temperature in the kidney; the faster the irrigation rate, the lower the temperature in the kidney [11]. The most striking result from this experiment is that when lithotripsy power and irrigation speed are varied together at a 1:1 ratio, the plateau temperature in the kidney stays below the safety threshold for all conditions. This approach is not only superior to the safety of the procedure but also provides physicians with a new way to adjust operational parameters in maximizing the benefit of lithotripsy while minimizing the possibility of thermal injury to the patient's kidney.\u003c/p\u003e \u003cp\u003eIn our work, the 20 W lithotripter power and an irrigation flow rate of 10 mL/min were considered, paying particular attention to ODC values in a large range from 50\u0026ndash;100%. This phenomenon is just the same as the classical sawtooth fluctuation wave which is corresponding to the laser periodical activation: the temperature in liquid increases rapidly when the laser is activated and decreases slowly to form a plateau when it is deactivated. The ODC ratio of the kidney showed a significantly raised level at the steady-state. This is similar to what was also observed in Louters et al. [13], so that a higher ODC increases temperature and energy release markedly. The steady-state renal temperature shows a trend of leveling off after attaining some value and does not increase further in case the ODC was kept below 70%. On the other hand, steady-state renal temperature increased to an increasing value after an ODC higher than 80%, and this may reflect increasing heat accumulation effect. It was also observed that a marked reduction in ODC, above an ODC of about 80%, considerably prolonged the time for which renal temperature to reach the safety threshold. This is likely due to the concordance with the results of Wanderling et al. [14]. The current theory is supported by the experimental results, which demonstrate that, over the very fine-tuning of the ODC required to minimize continuous activation time of the laser, the laser may be used for a greater length of time without crossing the safety temperature limit. One interesting point must be considered in this trial.\u003c/p\u003e \u003cp\u003eThe experiment used a fixed superpulsed thulium fiber laser, one diameter of the fiber, and a ureteral guide sheath with a flexible ureteroscope. The effect of fiber diameter on temperature and size of the soft sheath is an area for future research. In addition, the fact that this was an in vitro experiment does not bring into play the physiological factors in the changes in temperature, like renal irrigation and urine production. More studies are essential to clarify whether experiments on animals present a solution to this problem. In a nut shell, the outcome of the study has indicated that the decrease in ODC ratio from applying extracorporeal shock wave lithotripsy can have the effect of substantially reducing the rise in renal temperature. By adjusting the power in direct proportion to the lithotripsy and the irrigation rate in a 1:1 ratio, the renal temperature can be effectively kept within a safe range so as not to generate thermal damage to the tissue of the kidney. This may provide a new safe and effective method for clinical application in surgery.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eTherefore, reducing the ratio of ODC allows substantial relief in renal temperature elevation during super-pulse optical fiber thulium laser lithotripsy. When gravel power and irrigation speed have a 1:1 adjustment ratio, it can effectively keep renal temperature within safe limits, guarding against thermal injury of kidney tissue.\u003c/p\u003e "},{"header":"Declarations","content":"\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThere was no source of funding for this project.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eDing tianfu.Xu zheng.and Li jianxing. wrote the main manuscript text. Huang zhongyue. Xiao bo. and Huweiguo prepared all figures and table. All authors reviewed the manuscript\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eVentimiglia E, Robesti D, Bevilacqua L, Tondelli E, Oliva I, Orecchia L, et al. What to expect from the novel pulsed thulium:YAG laser? A systematic review of endourological applications. World J Urol. 2023. doi: 10.1007/s00345-023-04580-z.\u003c/li\u003e\n\u003cli\u003eKronenberg P, Traxer O. The laser of the future: reality and expectations about the new thulium fiber laser-a systematic review. Translational andrology and urology. 2019;8(Suppl 4):S398-s417. doi: 10.21037/tau.2019.08.01.\u003c/li\u003e\n\u003cli\u003eT\u0026uuml;rk C, Petř\u0026iacute;k A, Sarica K, Seitz C, Skolarikos A, Straub M, et al. EAU Guidelines on Interventional Treatment for Urolithiasis. European urology. 2016;69(3):475\u0026thinsp;\u0026minus;\u0026thinsp;82. doi: 10.1016/j.eururo.2015.07.041.\u003c/li\u003e\n\u003cli\u003eTraxer OA-O, Keller EA-O. Thulium fiber laser: the new player for kidney stone treatment? A comparison with Holmium:YAG laser. (1433\u0026ndash;8726 (Electronic)).\u003c/li\u003e\n\u003cli\u003ePeng Y, Liu M, Ming S, Yu W, Li L, Lu C, et al. Safety of a Novel Thulium Fiber Laser for Lithotripsy: An In Vitro Study on the Thermal Effect and Its Impact Factor. J Endourol. 2020;34(1):88\u0026ndash;92. doi: 10.1089/end.2019.0426.\u003c/li\u003e\n\u003cli\u003eSapareto SA, Dewey WC. Thermal dose determination in cancer therapy. Int J Radiat Oncol Biol Phys. 1984;10(6):787\u0026ndash;800. doi: 10.1016/0360-3016(84)90379-1.\u003c/li\u003e\n\u003cli\u003ePanthier F, Pauchard F, Traxer O. Retrograde intra renal surgery and safety: pressure and temperature. A systematic review. Current opinion in urology. 2023;33(4):308\u0026thinsp;\u0026minus;\u0026thinsp;17. doi: 10.1097/mou.0000000000001102.\u003c/li\u003e\n\u003cli\u003eAldoukhi AH, Ghani KR, Hall TL, Roberts WW. Thermal Response to High-Power Holmium Laser Lithotripsy. J Endourol. 2017;31(12):1308-12. doi: 10.1089/end.2017.0679.\u003c/li\u003e\n\u003cli\u003eRashid AO, Fakhulddin SS. Risk factors for fever and sepsis after percutaneous nephrolithotomy. Asian J Urol. 2016;3(2):82\u0026thinsp;\u0026minus;\u0026thinsp;7. doi: 10.1016/j.ajur.2016.03.001.\u003c/li\u003e\n\u003cli\u003eAlsyouf M Fau - Abourbih S, Abourbih S Fau - West B, West B Fau - Hodgson H, Hodgson H Fau - Baldwin DD, Baldwin DD. Elevated Renal Pelvic Pressures during Percutaneous Nephrolithotomy Risk Higher Postoperative Pain and Longer Hospital Stay. (1527\u0026ndash;3792 (Electronic)).\u003c/li\u003e\n\u003cli\u003eTokas T, Herrmann TRW, Skolarikos A, Nagele U. Pressure matters: intrarenal pressures during normal and pathological conditions, and impact of increased values to renal physiology. World J Urol. 2019;37(1):125\u0026thinsp;\u0026minus;\u0026thinsp;31. doi: 10.1007/s00345-018-2378-4.\u003c/li\u003e\n\u003cli\u003eWinship B, Wollin D, Carlos E, Peters C, Li J, Terry R, et al. The Rise and Fall of High Temperatures During Ureteroscopic Holmium Laser Lithotripsy. J Endourol. 2019;33(10):794-9. doi: 10.1089/end.2019.0084.\u003c/li\u003e\n\u003cli\u003eLouters MM, Dau JJ, Hall TL, Ghani KR, Roberts WW. Laser operator duty cycle effect on temperature and thermal dose: in-vitro study. World J Urol. 2022;40(6):1575-80. doi: 10.1007/s00345-022-03967-8.\u003c/li\u003e\n\u003cli\u003eWanderling C, Saxton A, Phan D, Doersch K, Shepard L, Schuler N, et al. WATTS happening? Evaluation of thermal dose during holmium laser lithotripsy in a high-fidelity anatomic model. World J Urol. 2024;42(1):157. doi: 10.1007/s00345-024-04821-9.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":" \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003csub\u003eODC\u003c/sub\u003e \u003csup\u003eS\u0026minus;S\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFirst time\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSecond time\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eThird time\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eFourth time\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eFifth time\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eSixth time\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e 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\u003cp\u003e45.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e \u003cp\u003e46.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.47\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e90%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e36.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e39.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e42\u0026thinsp;\u0026plusmn;\u0026thinsp;1.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e43.9\u0026thinsp;\u0026plusmn;\u0026thinsp;1.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e46.2\u0026thinsp;\u0026plusmn;\u0026thinsp;1.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e \u003cp\u003e47.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.58\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eTable.1 The laser gravel power is set to 20W and the irrigation speed is 10ml/min, the steady-state temperature in the kidney under the working cycle (ODC) of different agents (℃)\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Tabb\" border=\"1\"\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003csub\u003eTime\u003c/sub\u003e \u003csup\u003eODC\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e80%\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e90%\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e100%\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTime to reach the safety threshold\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e76.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e43.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e38.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1058.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eTable.2 The time required for different proportions of ODC to reach the safety threshold(s)\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"world-journal-of-urology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"wjur","sideBox":"Learn more about [World Journal of Urology](https://link.springer.com/journal/345)","snPcode":"345","submissionUrl":"https://submission.nature.com/new-submission/345/3","title":"World Journal of Urology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"superpulse fiber thulium laser, operator duty cycle (ODC), irrigation rate, Intrarenal temperature ","lastPublishedDoi":"10.21203/rs.3.rs-4724781/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4724781/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe present study aimed to examine the relationship of irrigation velocity, operator duty cycle (ODC), and intrarenal temperature during extracorporeal shockwave lithotripsy with a superpulse fiber thulium laser. Calcium oxalate monohydrate stones were implanted in the renal pelvis of fresh pig kidneys. Puncture technology was used to place a temperature probe accurately in the renal parenchyma about 2 mm away from the stone. To simulate the temperature at which a human body is exposed, that is, 37\u0026deg;C, the experiment was executed in an equilibrated laboratory at a constant temperature of 25\u0026deg;C with 60% humidity. The power of the laser varied between 10W and 30W; that of the irrigation varied from 10 to 30 ml/min. The time that the laser was applied was set at 120 s. Changes in the temperature were recorded online. A direct proportionality of temperature in the kidney to the rate of irrigation has been reported between 10 W and 30 W laser powers. The percentage ratio of the rate of irrigation and power in the laser is 1:1, which can keep the temperature in the kidney at a safe level. More specifically, at a laser power of 20 W and irrigation of 10 ml/min, the temperature inside the kidney increases sharply with the increase in ODC. By decreasing the ratio of ODC, the increase of temperature inside the kidney can be brought to a great reduction. The ratio of laser power to that of irrigation speed should be 1:1; hence, damage or injury to kidney tissue can be efficiently prevented from thermal changes.\u003c/p\u003e","manuscriptTitle":"Experimental study of irrigation rate, ODC and intrarenal temperature in superpulse fiber thulium laser lithotripsy","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-08-09 20:51:22","doi":"10.21203/rs.3.rs-4724781/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-08-15T12:32:05+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-07-31T13:59:27+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"20018496794383710108643456916660628392","date":"2024-07-22T19:51:59+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-07-22T16:15:20+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"271238438551727619887404094640140212249","date":"2024-07-21T07:37:35+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-07-19T06:20:09+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-07-16T18:19:18+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-07-16T16:28:46+00:00","index":"","fulltext":""},{"type":"submitted","content":"World Journal of Urology","date":"2024-07-11T14:25:36+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"world-journal-of-urology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"wjur","sideBox":"Learn more about [World Journal of Urology](https://link.springer.com/journal/345)","snPcode":"345","submissionUrl":"https://submission.nature.com/new-submission/345/3","title":"World Journal of Urology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"84a54faa-6118-4a49-a6cf-045d17dc6d0f","owner":[],"postedDate":"August 9th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-10-28T16:07:39+00:00","versionOfRecord":{"articleIdentity":"rs-4724781","link":"https://doi.org/10.1007/s00345-024-05289-3","journal":{"identity":"world-journal-of-urology","isVorOnly":false,"title":"World Journal of Urology"},"publishedOn":"2024-10-23 15:57:23","publishedOnDateReadable":"October 23rd, 2024"},"versionCreatedAt":"2024-08-09 20:51:22","video":"","vorDoi":"10.1007/s00345-024-05289-3","vorDoiUrl":"https://doi.org/10.1007/s00345-024-05289-3","workflowStages":[]},"version":"v1","identity":"rs-4724781","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4724781","identity":"rs-4724781","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}